I'll be honest right up front: I've never been a fan of vertical grips, especially those that bolt onto the camera after-the-fact. For most add-on grips, you're adding an additional layer of power connection that is more prone to failure. Plus even with the best designs I've seen, the screw-into-tripod-socket-plus-support-pins approach introduces just enough extra joint vibration potential that for tripod work I absolutely avoid them. I've also never quite understood why it's so desirable to have a bigger camera rather than just change your hand position for verticals. Even on a bigger DSLR, such as the D800, I have no real problem going from horizontal shooting to vertical; indeed, I get to the vertical position faster than if I had to change my hand position using a vertical grip.
That said, vertical grips are a popular accessory. Olympus makes one for the E-M5, for example, and we've seen third party options for other cameras, including today's news: the Ownuser NEX7 Grip*Controller (MIG-SNX7CPB). For US$180 you get a custom designed grip that bolts onto the bottom of the very small NEX-7 camera. Basically, you take your battery out of the camera, put the grip's dangling faux battery into the camera's battery holder and your battery into the grip itself, then you screw the grip into the tripod socket of the camera. What you get is a vertical grip with shutter release, plus an AC power in option and a remote control port.
You can order the device on Ownuser's page, or wait for all the eBay suppliers to pick it up in the coming weeks. Ownuser also makes grips for the GH2, NEX-5, and other cameras.